1. Field of the Invention
The invention is a new and distinct cultivar known by the cultivar epithet ‘Preble’ resulting from the novel hybridization of Salix viminalis with a hybrid of Salix sachalinensis×Salix miyabeana. The new cultivar was produced through controlled willow breeding conducted by the inventors in Syracuse, N.Y. The objective of the breeding program is to produce new willow cultivars that generate high biomass yields on a variety of sites, are resistant to diseases and pests, and possess agronomic traits suitable for mechanical planting, harvesting, and post-harvest processing. Shrub willow is being developed as an agricultural plant that will be grown and harvested as a sustainable, renewable source of energy. Once a field planting of shrub willows is established, the woody stems can be harvested every two to four years, and new shoots will re-sprout the following season. Repeated harvesting every two to four years can be sustained for at least 15 years.
2. Description of Relevant Prior Art
The invention is related to the following plant patents, all of which are assigned to the Research Foundation of the State University of New York: Fast-Growing Shrub Willow Named ‘Fish Creek’, U.S. Plant Pat. No. 17,710; Fast-Growing Shrub Willow Named ‘Canastota’, U.S. Plant Pat. No. 17,724; Fast-Growing Shrub Willow Named ‘Millbrook’, U.S. Plant Pat. No. 17,646; Fast-Growing Shrub Willow Named ‘Oneida’, U.S. Plant Pat. No. 17,682; Fast-Growing Shrub Willow Named ‘Otisco’, U.S. Plant Pat. No. 17,997; Fast-Growing Shrub Willow Named ‘Tully Champion’, U.S. Plant Pat. No. 17,946; and Fast-Growing Shrub Willow Named ‘Owasco’, U.S. Plant Pat. No. 17,845. The cultivar of fast-growing shrub willow named ‘Preble’ was produced in the same willow breeding program as were the other cultivars listed above.
This new cultivar of Salix viminalis×(Salix sachalinensis×Salix miyabeana) was the seedling progeny of the controlled pollination of the female clone Salix viminalis ‘SV2’ (unpatented) by the male clone Salix sachalinensis×Salix miyabeana ‘9970-037’ (unpatented) performed in February 2001 in Syracuse, N.Y. The plant has been propagated repeatedly by stem cuttings in Syracuse, N.Y. and has been found to retain its distinctive characteristics through successive generations of asexual propagation.
The parent clone Salix viminalis ‘SV2’ (unpatented) was originally transferred in 1990 from a breeding program in Toronto, Ontario, Canada to a willow breeding program in Syracuse, N.Y. and was vegetatively propagated from stem cuttings. The male parent, Salix sachalinensis×Salix miyabeana ‘9970-037’ (unpatented), was produced through controlled breeding in 1999 and is a progeny of Salix sachalinensis ‘SX61’ (unpatented) crossed with Salix miyabeana ‘SX64’ (unpatented). The growth of the parent plants was characterized in nursery plantings in Tully, N.Y. The male clone Salix sachalinensis×Salix miyabeana ‘9970-037’ (unpatented) displayed rapid stem growth and low incidence of rust disease, so was chosen to serve as a parent in a cross with S. viminalis ‘SV2’(unpatented), which suffered from susceptibility to the potato leafhopper (Empoasca fabae). The seedlings produced by this cross (identification #01X-268) were first established in a greenhouse, and then were transplanted to a field in Syracuse, N.Y. This particular individual (identification #01X-268-015) was selected from the family due to its exceptional stem height growth.
The new cultivar has been grown in Syracuse, N.Y. and Tully, N.Y., which have a normal yearly average daily temperature of 47° F., normal daily maximum temperature in July of 82° F., normal daily minimum temperature in January of 14° F., and average precipitation of 40 inches. The new cultivar grows from a rooted cutting to a fully mature plant ready for harvest in approximately two to four years.
This cultivar was described as displaying greater salt tolerance than many other Salix spp. genotypes in a paper by R. D. Hangs, J. J. Schoenau, K. C. J. Van Rees, and H. Steppuhn “Examining the salt tolerance of willow (Salix spp.) bioenergy species for use on salt-affected agricultural lands” (2011) Canadian Journal of Plant Science, 91:509-517.